1. [单选题]5． The number of the students in our class_______45．
A. are
B. is
C. to be
D. go to
2. [单选题]下列物质中，不能在氧气中燃烧的是（ ）
A. 金箔
B. 铁丝
C. 木炭
D. 氢气
3. [单选题]3． —Tony，your bag is still on your desk．—Oh，thank you． I have forgotten _________ it there．
A. to put
B. to putting
C. put
D. putting
