We will go for a picnic if it (not rain)tomorrow

We will go for a picnic if it 【doesn't rain】tomorrow。 再问： They (plan)a birthday party for Mr。Green at thr moment 再答： They were planning a birthday party for Mr。Green at the moment。 at the moment最好还是用过去进行时，比现在进行时更好。如果你们没有学过过去式，那就are planning Who (teach)them Chinese？Miss Gao。 Who【teaches/is teaching】them Chinese？Miss Gao。 teaches意思是每天教，is teaching意思是谁正在教