You will notice that the mood we call the polite imperfect ends in -masu for all the verbs (-su for the copula); the polite perfect ends in -mashita for all the verbs (-shita for the copula); and the polite tentative ends in -mashō for all the verbs (-shō for the copula). The verb forms that appear before these polite endings are called infinitives (or pre-masu forms), and they all end in the vowel -e or -i. See 4.3 and 4.8 for more about infinitives. The plain gerund ends in -te or -de (no ending for the copula), and there are certain changes in the verb stem itself.

3.10. Use of the gerund (or te-form)

      The gerund is often called the te-form. It is used before kudasai ‘please’ to make a polite request, for example:

      もう一度言ってください。

       Mōichido itte kudasai.

      Please say it again.

      The gerund is used with the particle kara to mean ‘after (do)ing.’ For example:

      ご飯を食べてから新聞を読みました。

       Go-han o tabete kara shinbun o yomimashita.

      After eating, I read my newspaper.

      The gerund is also used alone at the end of a clause to mean ‘does/did/will do … and…,’ for example:

      オフィスへ行って, メールを読みます。

       Ofisu e itte, mēru o yomimasu.

      I go to the office and read my e-mails.

      The gerund is used in verb phrases with some form of the verb imasu to mean ‘is (do)ing,’ expressing a kind of “process” or “continuing action” and focusing on the fact that the action lasts for a while. For example:

      今ご飯を食べています。

       Ima go-han o tabete imasu.

      I’m eating now.

      The simple verb form, on the other hand, focuses our attention on the action itself, either a specific act (Nani o tabemasu ka ‘What do/will you eat?’; Sakuban benkyō shimashita ‘Last night I studied’) or a series thought of as a set of specific acts (Mainichi hatarakimasu ‘Every day I work’) rather than as a set of continuing actions taking up a space of time (Mainichi hataraite imasu ‘Every day I’M WORKING’). The exact difference between shigoto o shimasu and shigoto o shite imasu is just as subtle as that between ‘I work’ and ‘I’m working,’ and in many situations either phrase would seem appropriate. Sometimes the difference between the simple verb and the GERUND + imasu seems to lie in a slightly different focus of emphasis. In the sentence Ichi-ji kara ni-ji made hatarakimashita ‘I worked from 1 o’clock to 2 o’clock,’ the principal emphasis is on the fact that I worked and the time is incidental additional information. But in the sentence Ichi-ji kara ni-ji made hataraite imashita ‘From 1 o’clock to 2 o’clock I was working,’ the emphasis, while perhaps really focused on the DURATIVE nature of the action, that is, on the word imashita, seems to be more on the time and what I was doing during the time.

      The gerund is also used in certain phrases with other verbs:

      歩いて行きます。

       Aruite ikimasu.

      He walks (He goes walking).

      車に乗って来ます。

       Kuruma ni notte kimasu.

      He comes by car (riding in a car).

      マイクをつれて行きましょうか。

       Maiku o tsurete ikimashō ka.

      Shall I bring Mike along (Shall I come bringing Mike)?

      Notice that the gerund has no perfect, imperfect, or tentative meaning of its own but takes on the mood of the following (or final) verb.

      旅行しています。

       Ryokō shite imasu.

      I am traveling.

      旅行していました。

       Ryokō shite imashita.

      I was traveling.

      旅行していましょう。

       Ryokō shite imashō.

      Let’s keep traveling.

      公園へ行って散歩しましょう。

       Kōen e itte sanpo shimashō.

      Let’s go to the park and take a walk.

      公園へ行って散歩しました。

       Kōen e itte sanpo shimashita.

      I went to the park and took a walk.

      公園へ行って散歩しませんか。

       Kōen e itte sanpo shimasen ka.

      Won’t you go to the park and take a walk?

3.11. Use of the imperfect, perfect, and tentative moods

      The imperfect mood (sometimes called the present tense or non-past tense) indicates that an action has not been completed: it may or may not have begun, but it must be a definite, decided action. In the following sentence, we use the imperfect because I’m still sick today:

      昨日から病気です。

       Kinō kara byōki desu.

      I’ve been sick since yesterday.

      In the following sentence, perhaps you haven’t even started to go yet, but it’s definite that you will go:

      どこへ行きますか。

       Doko e ikimasu ka.

      Where are you going?

      On the other hand, the perfect mood (sometimes called the past