这样写对吗?不对怎样改正Tom is at his desk. He is studying right now .To

Tom is at his desk.He is studying right now .
Tom had(have) some homework to do ,so he (also)studied last night
Tom is going to begin studying(to study最好用不定式) at 7:00 tomorrow ,his friends are going to come over at 7:30.
Tom has been studying when they arrive
看了两次.没问题了,

Tom is at his desk. He is studying right now .(对)
Tom had some homework to do ,so he studied last night 对
Tom is going to begin studying（改成to study） at 7:00 tomorrow ,his friends are going to come over at 7:30.Tom has been studying when they arrive(arrived)