题目

切下燕麦的芽尖，与琼脂接触一段时间后，将琼脂切成小块，放在切去芽尖的胚芽鞘切面的右侧，能看到的现象是 A．自然生长      B．停止生长        C．向右弯曲生长      D．向左弯曲生长 答案：D—Dad, I've tried my best but I still can't solve these problems.—Don't worry, my son. No one is ________ and everyone fails from time to time.A.successfulB.confidentC.perfectD.excellent