大多数蛋白质的含氮量平均为()
A.10%
B.12%
C.16%
D.18%
E.20%
参考答案:C
-------- ________ Daniel ________ glasses? -------- Yes, he ________.
A.Do, put on; is
B.Does, wear; wears
C.Does, wear; does
D.Does,have; do
光纤是一种直径为()μm柔软的传导光波的介质,一般由玻璃纤维和塑料构成,在折射率较高的纤芯外面,再用折射率较低的包层包住,再在包层的外面加上一层保护套,就构成了一根单芯光缆。
A.50~100
B.1~20
C.20~50