下列叙述中正确的是
| A．能使润湿的淀粉KI试纸变成蓝色的物质一定是Cl2 |
| B．某溶液加入CCl4，CCl4层显紫色，证明原溶液中存在I－ |
| C．某溶液加入BaCl2溶液，产生不溶于稀硝酸的白色沉淀，该溶液一定含有Ag+ |
| D．液溴易挥发，在存放液溴的试剂瓶中应加水封存 |
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 can’t leave. She told me that I ______ stay here until she comes back.
| A．can | B．must | C．will | D．may |
—— Do you mind my opening the window? It’s a bit hot in here.
—— ______ , as a matter of fact
| A．Go ahead | B．Yes, my pleasure |
C．Yes, I do | D．Come on |