在牧业上，想要获得更多的肉类和其他畜产品，首先要提高草原生态系统中的______。
参考答案：第一性生产力
—How about going hiking this weekend?
—Sorry, I prefer ___________ rather than ____________.
A. staying at home; go out B. to stay at home; go out C. to go out; stay at home
产卵荚的昆虫是
A．臭虫B．蜱C．麻蝇D．蜚蠊E．蚤
