题目

用方框中所给的频度副词填空 sometimesoftenusually alwaysnever （1） My father eatshealthy food, so he is very healthy. （2） Dave goes toHong Kong, so he wants to go there. （3） I have dinnerat home, but I have dinner in the restaurants with my friends. （4） — What time do you go to bed?— At about nine thirty. 答案：【1】always 【1】never 【1】usually【2】sometimes 【1】often如图所示，矩形ABCD中，点E在CB的延长线上，使CE=AC，连接AE，点F是AE的中点，连接BF、DF，求证：BF⊥DF．