一般认为，生油物质主要是（）
A、水生低等生物
B、水生物
C、浮游生物
D、各种微生物
参考答案：A
There is ______ water in the glass. Let's go and get some. [ ]
A. few
B. much
C. many
D. little
90% of the credit amount must be paid ____________ the presentation of documents.
