第一节：单项填空（共15个小题,每小题1分,满分15分）
从A、B、C、D四个选项中,选出可以填入空白处的最佳选项。
1. —I think our headmaster should be invited to the party.
— __________. He will be treated as our honored guest.
A. It9s up to you B. I agree absolutely
C. You must be joking D. It doesn't matter
2. The failure was a（n）_________ to him, but he wasn't discouraged and soon got as positive as ever.
A. important factor B. major issue C. heavy blow D. serious danger
3. Reading in English is an excellent way to __________ your vocabulary.
A. mention B. enter C. enhance D. spell
4. Exactly _________ the potato was introduced into Europe is uncertain, but it was probably around 1565.
A. whether B. why C. how D. when
