题目

This is a street crossing. There are red and green lights at each corner. Drivers must watch the lights carefully.When there is a green light, the cars may go. When there is a red light, the cars must stop. They must wait until the red light changes to green. Then they can go on. Sometimes the cars want to make a right turn or a left turn. They can make a right turn when the light is green or red. But they must wait until the green light is shining if they want to turn left.Some people are color-blind(色盲). They can not tell the difference(不同) between the red and green lights. These peo下图中a表示基因工程，c表示发酵工程，d表示克隆技术，则e和b分别表示A．胚胎移植和细胞培养B．显微注射技术和细胞培养C．细胞培养和花粉离体培养D．显微注射技术和药粉离体培养