资源简介
（友情提示：鼠标拖选单词即时翻译）
1. The original patent for a refrigerating machine was issued in 1834 to Jacob Perkins, ______ American engineer.
A. a B. an C. the D. /
2. You have yet to answer my question _________ I can count on your vote.
A. that B. if C. whether D. /
3. The weather forecast is not for cooler weather; ______, it is expected to be warmer.
A. if anything B. if ever C. if at all D. if only
4. —Have you been to South Africa?
—No, I ______ last year, but Dad wouldn’t let me.
A. were to go B. was gone C. went D. was to have gone