七国之乱发生在哪位皇帝在位时 [ ]
A．汉高祖
B．汉文帝
C．汉景帝
D．汉武帝
答案：C
You’ve failed to do what you _____ to and I’m afraid the teacher will blame you.
A．will expect
B．will be expected
C．expected
D．were expected
原始生命起源于
A．原始大气
B．有机小分子物质
C．有机大分子物质
D．非生命物质
