水稻进入有效分蘖临界叶位,11叶品种()叶,预计田间茎数达计划茎数()时,在()叶期开始晾田控蘖,控制()叶的同伸分蘖发生。
参考答案:8;80%;7;9
设Sn是等比数列{an}的前n项和,若S1,2S2,3S3成等差数列,则公比q等于( ).
The five rings on the Olympic flag ______ the five continents that are joined together in the Olympic Games.
A.belong to
B.stand for
C.take apart
D.pack up