（一）
1.—He must be busy doing his homework right now.
—I imagine____.
A. that B. to C. so D. it
选C。I imagine so=I think so,
2. Mary had promised to give me a ticket for tomorrow. She failed, ____.
A. either B. though C. but D. too
选B。结合上下文意思我们可以知道本题表示转折关系，先排除A、D；而but为并列连词通常放在句首或句子中间起连接作用。故选B。
