如图所示,起重机的挂钩用四根等长的绳子吊起质量为m的物体,绳子与竖直方向均成30°角,则每根绳子中的张力大小为
A.mg
B.
C.
D.
答案:C
The museum is ___ far ____ it will take us half an hour to get there by bus.
A.such... that
B.as...as
C.so...that
D.so … as
立正垂手中指端取的穴位是:
A.殷门
B.气冲
C.合阳
D.风市
E.阴包