影响目的基因在大肠杆菌中表达的因素.
参考答案：
1.外源基因的拷贝数2.外源基因的表达效率3.表达产物的稳定性4.细胞的代谢负荷
汉武帝时，在长安设立太学，从中选拔官吏。太学的学生们日常主要研读的应该是： [ ]
A、《道德经》
B、《五经》
C、《孙子兵法》
D、《法经》
China won't be a fast-growing but fragile country. It has to develop it's military strength in order to make
any power think twice _____ trying to offend China's key interests. [ ]
A. before
B. when
C. while
D. until
