读太阳系示意图，回答：

小题1:目前，人类已经实地考察的宇宙天体是

A．ab

B．de

C．fg

D．hi小题2:图中包含的天体系统层次有

A．一级

B．二级

C．三级

D．四级

Which of the following is true according to the speaker().

A.We have extra time to complete the assignment.

B.We won’t see the professor until next week.

C.The professor asks us to turn in the papers within a week