30. Only those who have experienced hardship ____ well aware of what happiness means. 

A．can they be

B．they can be

C．can be

D．they can

成为法国大革命建立资本主义正常统治秩序转折点的是（）

A.瓦尔密大捷

B.雅各宾派专政开始

C.“热月 * * ”

D.“雾月 * * ”