Use verb in the correct form
- Scientists (to develop) rocket technology already.
- Today it (to be) popular to have a PC at home.
- Students (to use) the Internet now.
- Students (to make) difficult experiments the whole day yesterday.
- Our teacher (to write) a new program today.
- We (to do) difficult experiment next week.
- E-mail (to be) the most popular service in the Internet.