组成酶
参考答案：
根据酶的合成方式和存在时间，微生物细胞内的酶可分为组成酶和诱导酶，组成酶是细胞内一直存在的酶，它的合成仅受遗传物质控制即受内因控制。
Foreign visitors will be amazed ______ the art work of three cowboys on horseback ______ a
crowd of cows back home along a road on the Rocky Mountains on one broad maple leaf. [ ]
A. seeing; driving
B. to see; to drive
C. to see; driving
D. seeing; to drive
