用计算器计算：－6.25＋（－3.41）－31.7．

a．胚芽鞘尖端合成生长素        b．胚芽鞘尖端感受光刺激；

c．胚芽鞘向光弯曲生长          d．生长素在背光一侧分布较多；

e．背光一侧细胞生长较快        f．单侧光照射胚芽鞘尖端．

阅读下面的诗歌，完成后面的题目。

                                                                                                        江 上

                                                                                                 （宋•王安石）
                                                                                                 江北秋阴一半开，

                                                                                                 晚云含雨却低徊。

                                                                                                 青山缭绕疑无路，

                                                                                                 忽见千帆隐映来。

____应该   如：We are supposed to stop smoking. 我们应该停止吸烟。

知识拓展   表示"应该"的词有：should, ought to，be supposed to