The combination of the "te" form of a verb with "iru" (for present tense) or "imasu" (for polite present tense) is used to express ongoing or continuous actions in Japanese. This construction is equivalent to the English present progressive tense, where we use "is/are + verb-ing.”

Take the て form and add いる for non-polite present tense or います for polite present tense.

Past Form

The combination of "て" form with "いる" (for present tense) or "います" (for polite present tense) can have a past form. The past tense for this construction is formed by using the "て" form with the past auxiliary verb "いた" (for plain past) or "いました" (for polite past).

For example, let's consider the verb "食べる" (taberu) - to eat:

• Present Progressive (non-polite): 食べている (tabete iru) - is/are eating
• Polite Present Progressive: 食べています (tabete imasu) - is/are eating

To form the past tense:

• Past Progressive (non-polite): 食べていた (tabete ita) - was/were eating
• Polite Past Progressive: 食べていました (tabete imashita) - was/were eating

So, the "て" form with "いる" or "います" can indeed have a past form using the appropriate past auxiliary verbs.

Negative

The negative form of the "て + いる/います" construction is created by using the negative form of the verb "いる" or "います" along with the "て" form of the main verb. Here's how it works:

For the plain negative form (non-polite):

• Use the negative form of the verb "いる" (いない) with the "て" form of the main verb.

Example with the verb "食べる" (taberu) - to eat: