《明史》记载：“然品类既烦，名称多杂，或一物而析为二三，或二物而混为一品，时珍病之。乃穷搜博采，芟烦补阙，历三十年，阅书八百余家，稿三易而成书，曰《本草纲目》。”上述材料不能显示李时珍在编写《本草纲目》时(  )

关于烷烃性质的叙述中，不正确的是（     ）

“疑是地上霜”的“疑”的意思是（   ）。

    As they walk down the halls during their years together at Shady Side, our boys and girls —— so soon to become men and women —— are learning to think, to work, to question, to be ____ and ____, to____with others, to laugh at their mistakes and to act ____ when ____ comes their way.

    Sir William Osler, a famous Canadian doctor,____ the value of ____ by saying, "No man is really happy ____ a hobby, and it makes precious little ____ what the outside ____ may be."