当前和今后一个时期国际局势发展的基本态势是

A．总体和平、局部战乱
B．总体缓和、局部紧张
C．总体稳定、局部动荡
D．总体发展、局部停滞

Charles is believed_______ the floor yesterday; he is always helping others silently. 

A．to sweep

B．to have swept

C．having swept

D．swept