如图所示为一物体作直线运动时的图象，但纵坐标表示的物理量未标出．已知物体在前2s时间内向东运动，则以下判断正确的是（　　）

A．若纵坐标表示速度，则物体在4s内的位移为前2s位移的2倍

B．若纵坐标表示速度，则物体在4s内的加速度大小不变，方向始终向东

C．若纵坐标表示位移，则物体在4s内的运动方向始终向东

D．若纵坐标表示位移，则物体在4s内的位移为零

用所给词的适当形式填空

小题1:I helped my parents __________(do) some housework yesterday.

小题2:Do you think it is good for animals __________(live) in a zoo?

小题3:How about __________(visit) the museum this afternoon?

小题4:I __________ (have) a fever yesterday.

小题5:They are too young. They can’t look after ___________(they).

小题6:The cat has four ___________ (foot).

小题7:It's important ________ (learn) the language.

小题8:I want to learn how ________( run) quickly.

小题9:The little boy is _________ (interest)  in the ____________(interest) story.

小题10:Paul is very funny. He often makes us _______ (laugh).