A:含2个氢分子
B:硼元素的化合价为+3
C:只含一种非金属元素
D:Na、B、H的质量比为1:1:4
——Would you like to go shopping with me?——I'd love to, _____I can't. I have a lot of homework to do.
537-375≈____ 256+632≈____
①细胞膜 ②线粒体 ③核糖体 ④中心体 ⑤高尔基体 ⑥内质网 ⑦液泡 ⑧叶绿体 ⑨溶酶体
— Who taught ________to make a home page?
— Nobody, I taught ________.