题目

---Have you seen Dr. Adams recently? ---No. He __________ Hong Kong for an important meeting. He’ll come back tomorrow. A. has gone in         B. has been in       C. has gone to      D. has been to 答案：C下图为桃切面图，图中所示结构a是由下列什么结构发育而来的 [     ]A．胚珠         B．子房        C．受精卵      D．子房壁