在称量塑料瓶质量实验中，天平恢复平衡并记录塑料瓶质量后，小明将塑料瓶剪碎再重新放回天平，则（　　）

A．塑料瓶质量减小

B．塑料瓶质量增大

C．塑料的密度减小

D．天平仍保持平衡

用所给词的适当形式填空.（10分）

小题1:He is very lazy.He _________his homework every day. ( not do )

小题2:Lucy _________ the piano when I went to see her last night. ( play )

小题3:Listen! Someone            (cry) in the next room.

小题4:He told me that the sun       (rise) in the east.

小题5:We’ll go to the beach if it            (not rain)tomorrow.

小题6:     ( not be ) late for school.

小题7:The short play             (write) by Lu Xun in 1932

小题8:My mother went out an hour ago.she            (be)back in half an hour.

小题9: you      (finish)your work? —— Not yet.

小题10:Li Ming       (read ) this book two days ago.