下列实验能够直接用于验证质量守恒定律的是（   ）

如图所示的是细胞的生长、分裂和分化过程。其中①、③分别表示细胞的（　　）

   2³²﹣1可以被10和20之间某两个整数整除，则这两个数是（   ）

选出与所听句子相符的图片（  ）

短文改错。
短文中共有10处语言错误，每行中最多两处错误。错误涉及一个单词的增加、删除或修改。
增加：在此处加一个漏字符号(∧)，并在其下面写出增加的词;
删除：把多余的词用斜线(＼)划掉;
修改：在错的词下划一横线，并在其下面写出修改后的词。
注意：1）.每处错误及其修改均仅限一词；
2）.只允许修改10处，多者(从十一处起)不计分。
    I am angry about the behavior of dishonest in exams. This doesn't mean I've never cheated. I once write the answers on my hand for a history test, but unluckily caught by my teacher. Because she was one of my most favorites, there were no words to describe what sorry I felt at that time. I thought cheat would help me keep my straight A. Little I know that I was hurting not only me but also my teacher. From this lesson I know our teachers want their students to succeed by learning with their own and do the best they can, not by cheating.