1/ didn't go
2/ is
3/ start
4/ collecting
1. Mary (not go) ………didnt go………………..to school yesterday because she was sick.
2. If it (be)…………is……….sunny, we will go on a picnic.
3. We might not (start)………start………..our dinner until Jack arrives.
4. How about (collect)…………collecting………..old book and clothes?