— How long have you been here?
—About half an hour, Jack ______me here.
A:had driven
B:has driven
C:drives
D:drove
下列说法不正确的是( )
图为几种细菌和真菌的结构模式图,请仔细观察,回答下列问题.
如图,轻绳OA一端系在天花板上,与竖直方向夹角37°.轻绳OB水平,一端系在墙上,结点O处挂一重为40N的物体.