题目

如图1，线段AC＝6cm，线段BC＝15cm，点M是AC的中点，在CB上取一点N，使得CN：NB＝1：2，求MN的长．                答案：解：∵M是AC的中点，AC＝6， ∴MC＝AC＝6×＝3，·············································································· 1分 又因为CN∶NB＝1∶2，BC＝15， ∴CN＝15×＝5，····························································�— My father spends lots of time ________ with my grandmother on weekends.— Really? He is a good son. A．sayingB．listeningC．chattingD．singing