沼气发酵是指有机物在厌氧条件下，通过单一细菌的分解代谢，最终产生沼气的过程。
参考答案：错
巨大儿的定义为：出生体重超过（）
A.3200g
B.3500g
C.4000g
D.4200g
E.4500g
If he________quietly as the doctor instructed,he would not suffer so much now.[ ]
A. lies
B. lay
C. had lain
D. should lie
