冈崎片段的长度约为:
A.100~200 bases B.500~800 basesC.1000~2000 bases D.5000~8000 bases
参考答案:C
Walking alone in the dark, the boy whistled to ________ his courage. [ ]
A. hold up
B. keep up
C. set up
D. take up
罗伦兹因数是表示什么对衍射强度的影响?其表达式是综合了哪几方面考虑而得出的?