葡萄糖或氨基酸逆浓度梯度跨细胞膜转运的方式是
A.原发性主动转运
B.继发性主动转运
C.经通道易化扩散
D.经载体易化扩散
参考答案:B
The number of people who speak English ______ large, and a large number of people _______ native speakers.
A.are ; are
B.is ; are
C.is ;is
D.are ;is
定位器主要有挡铁、支撑钉、定位销、V形块、定位样板5类。其中()主要用于焊件依孔的定位。
A.挡铁和支撑钉
B.定位销
C.V形块
D.定位样板