若方程3x2m+1-2y=7是二元一次方程，则m=______．
根据二元一次方程的定义可知：2m+1=1，
解得：m=0．
故答案为：0．
用所给词的正确形式填空。
1. It is interesting _________ (know) something about animals.
2. __________ (not open) the door. It is cold outside.
3. She can work out the difficult question _________ (easy)
4. Please keep ___________ (quietly) in the reading - room
5. —Where is my cup?
—__________ (you) is over there.
6. What about _________ (go) fishing with us tomorrow?
海运险的基本险分平安险、（）和一切险三种。
A.卖方利益险
B.淡水雨淋险
C.水渍险
D.渗漏险
