某有机化合物结构如下，分析其结构并完成下列问题：(1)写出其分子式_________。(2)其中含有_________个不饱和碳原子，分子中有_________种双键。(3)分子中
— What are you looking for, James?—____football. It’s time for me to play football with my friends. A.The； a B.A； the C. The； / D. / ； /
— I don’t think we can find a new day to work out the problem. — But we’d better not . A. end up B. hand out
_____, John returned to school from his hometown. A．The summer vacation being over B．The summer vacation is over C．Because the summer vacation over D．After the sum
某学生用化学知识解决生活中的问题，下列家庭小实验不合理的是 A．用食醋除去暖水瓶中的薄层水垢 B．用米汤检验食盐是否为含碘盐 C．用纯碱（Na2CO
As director of the company，I can’t three weeks away from work. A.carry B.cost C.pay D.afford
下列运算正确的是（ ▲ ）A．；B．（为实数）；C．；D．．
The mother forbids noise in our study，but she doesn’t forbid us____ a discussion． A、to make；to have B、making；to have C、making；having D、make；having
