1.Students__（can/must)finish their homework on time.its a rule 2.The train is leaving.I am
问题描述：
1.Students__（can/must)finish their homework on time.its a rule 2.The train is leaving.I am
afraid I__(can/have to)go now.
3.Jessica is a good student.She__(usually/never) gets to school early
答
1.Students_must_（can/must)finish their homework on time.its a rule
2.The train is leaving.I amafraid I_have to_(can/have to)go now.
3.Jessica is a good student.She_never_(usually/never) gets to school early