A:神经调节
B:体液调节
C:神经—体液调节
D:激素调节
试写出﹣2x2y的一个同类项,则这个同类项可以是____( 写出一个即可)
--I think it's really necessary. It is reported that the food that Chinese people
every year is enough to feed 200 million people for a year.
菜青虫四个发育阶段中,对菜青虫危害最大的阶段是____,有发生蜕皮现象的阶段是____(本小题全填序号).