下列关于甲烷分子结构的叙述中，正确的是
A．甲烷分子中C、H原子间为离子键
B．甲烷分子的空间结构是正方体
C．甲烷的结构式为CH4
D．甲烷分子中4个碳氢键完全相同
They use computers to keep the traffic _______ smoothly.
| A．being run | B．run | C．to run | D．running |
If you leave the club, you will not be_____back in .
| A．received | B．admitted | C．turned | D．moved |
What I need is_____ book that contains ______ABC of oil painting.
| A．a; 不填 | B．the; 不填 | C．the; an | D．a ; the |
Jenny nearly missed the flight______ doing too much shopping.
| A．as a result of | B．on top of | C．in front of | D．in need of |
The CDs are on sale! Buy one and you get ______ completely free.
| A．other | B．others | C．one | D．ones ks |