()和()被称为魔斑分子,它作为()酶的别构效应物调节此酶的活性。
参考答案:ppGpp、pppGpp、RNA聚合酶
单项选择。
They want me ____ a song at the party. [ ]
A. sing
B. to sing
C. sings
D. singing
电力设备维修必须遵守哪些规定?