人群疾病的自然史研究，可见于下列哪一项研究A、病例对照研究B、实验研究C、横断面研究D、队列研究E、

劣质品种往往表现的的特征为()。

A.叶片较大，叶长是叶宽的2倍左右，主脉粗细适中

B.油分丰满，组织疏松，颜色金黄，光泽鲜明，叶片厚薄适中

C.长相较差,叶片大小、叶形、厚度不合理

D.油分丰满，组织疏松，颜色较淡，光泽较暗，叶片较厚或较薄

此题为多项选择题。请帮忙给出正确答案和分析，谢谢！

Which of the following sentences is NOT an emphatic sentence？

A．This is the very question that deserves careful analysis.

B．It is stability that destroys people"s ambition and barricades people"s steps.

C．He will have it that our plan is really practical.

D．It was not until his wife came back that he went to bed.

请帮忙给出正确答案和分析，谢谢！

下列关于白肋烟的叶面与质量关系的描述不正确的是()。

A.上部叶叶面平展

B.中部叶叶面平展

C.下部叶叶面平展

D.皱缩的烟叶燃烧性好

此题为多项选择题。请帮忙给出正确答案和分析，谢谢！

The study from the Teacher Training College in Bilbao Spain shows that______.

A．some people were much wiser when they were young

B．climate change is a subject that affects every member of human society

C．climate change is the greatest hoax to people from all over the world

D．people pay less attention to the environment when they become older

请帮忙给出正确答案和分析，谢谢！