设氯原子的质量为ag，12C原子的质量为bg，用NA表示阿伏加德罗常数的值，则下列说法正确的是
| A．氯元素的相对原子质量为12/b | B．mg该氯原子的物质的量为m / NA mol |
| C．该氯原子的摩尔质量是a NA | D．ng该氯原子所含的电子数是17n/a |
Progress______ so far very good and we are sure that the work will be finished on time.
| A．was | B．had been | C．has been | D．will be |
Charles was alone at home, with_______ looking after him.
| A．someone | B．anyone | C．not one | D．no one |
It is often ______ that human beings are naturally equipped to speak.
| A．said | B．to say | C．saying | D．being said |
I’m sure that your letter will get______ attention. They know you’re waiting for the reply. 
| A．continued | B．immediate | C．careful | D．general |
All the dishes in this menu, ______ otherwise stated, will serve two to three people. 
| A．as | B．if | C．though | D．unless |