Mr. Chen is very _________ every day. He has no time to help his daughter with her homework.
A:tired
B:relaxing
C:busy
D:free
制作临时玻片标本的主要步骤可以依次简化为( )
①—月 ____ .
②二月 ____
③三月 ____
④四月 ____
⑤五月____
⑥六月____
如图所示,电能表的示数是____ kW•h
Listen! The birds ____ ____( sing ) in the tree .