A:一个圆
B:两个圆
C:半个圆
D:两个半圆
如图所示,灯重30 N,灯挂在水平横杆的C端,O为杠杆的支点,水平杆OC长2 m,杆重不计,BC长0.5 m,绳子BD作用在横杆上的拉力是多少?(∠DBO= 30°)
Who could have _______ that within 10 years he'd be in charge of the whole company?
58 ____ 59
919 ____ 1019
1____ 89
2 45 ____2.8.
一个人有缺点并不可怕,关键是( )