【简答题】如果两集合A 1 和A 2 都是可数的,证明:A 1 ×A 2 也是可数的.
【单选题】---- If I work hard at all my lessons from now on, will I do better in them? ---- Sure, _________.
A.
Practice makes perfect
B.
Better late than never
C.
You’re never too old to learn
D.
The early bird catches the worm
【判断题】十八大提出,法治是治国理政的基本方式。要推进科学立法、严格执法、公正司法、全民守法,坚持法律面前人人平等,保证有法必依、执法必严、违法必究。()
【单选题】以从事同一行为的团体成员(如球队队员、自愿消防队队员等)为承保对象的团体健康保险被称为( )。
【单选题】If I ______ hard at school, I ______ an engineer, too.
A.
worked ; would have been
B.
had worked; would have been
【多选题】党的十九大报告指出的公民四权是指:( )
【简答题】证明:有限集A和可数集B的笛卡儿积A×B是可数集.