A:
B:
C:
D:
多音字组词
传chuán ____ zhuàn ____
降jiàng ____ xiáng ____
数列{an}满足a1=1,且an+1-an=n+1(n∈N*),则数列{1an}的前10项和为 ____ 。
This coastal area a national wildlife reserve last year.( )