中生代陆地上繁盛的动植物分别是（    ）

   A pretty, well-dressed young lady stopped a taxi in a big square, and said to the driver, “Can you see that young man at the other side of the square?”
   “Yes,” said the taxi-driver. The young man was standing outside a restaurant and looking impatiently at his watch every few seconds.
   “Take me over there.” said the young lady.
   There were a lot of cars and buses and trucks in the square, so the taxi- driver asked, “Are you afraid to cross the street.”
   ‘Oh, no !” said the young lady. “But I said that I would meet that young man for dinner at one o’c1ock, and it is now a quarter to two. If I arrive in a taxi, it will at least seem as if I have tried not to be too late.”

一年之中太阳直射的最北界线是（    ）