下列不具有弹力的物体是( )
A:自然状态的弹簧
B:被压弯的竹枝
C:拉开的弓
D:拉长的橡皮筋
已知关于x的不等式组 恰有5个整数解,则t的取值范围是( )
下列所示的四种现象中,可用光的直线传播原理解释的是( )
⑴I'm hungry.____ A. She's running.
⑵What are you doing?____ B. He's making noodles.
⑶What are they doing?____ C. I'm hungry, too.
⑷What is she doing?____ D. They are rowing a boat.
⑸What is Sam doing?____ E. I'm reading a book.