Раскройте скобки, употребляя глаголы в present continuous, past continuous, future continuous tenses. 1. i (to write) a letter to my granny now. 2. my sister (to swim) in the pool from 5 till 6 o'clock yesterday. 3. my friends (to ski) in the caucasus next weekend. 4. she still (to type) her article. 5. they still (to drink) tea in the canteen.

Определяем время, выбираем be в нужной форме и глагол с окончанием -ing:
1. Настоящее -> am writing
с точным указанием временного отрезка -> was swimming
3. Будущее, без точного указания временного отрезка (планируемое действие) -> is skiing
4. Настоящее -> am typing
5. Настоящее -> are drinking