有常温下物质的量浓度均为0.1 mol/L的①氨水②NH4Cl溶液③Na2CO3溶液 ④NaHCO3溶液,下列说法正确的是（ ）
| A．4种溶液pH的大小顺序:①＞④＞③＞② |
B．等体积的①和②溶液混合后若pH＞7:c(Cl-)＞c(N ) |
| C．溶液①、③由水电离产生的c(OH-):①＜③ |
D．溶液③、④等体积混合后,溶液中c(C )＞c(HC ) |
His sister left home in 1998, and _______since. 
| A．had not been heard of | B．has not been heard of |
C．had not heard of | D．has not heard of |
What do you mean, there are only ten tickets? There _____ be twelve
| A．should | B．would |
C．will | D．shall |
Could I speak to ______ is in charge of International Sales please?
| A．who | B．what |
| C．whoever | D．whatever |
How much _______ she looked without her glasses!
| A．well | B．good | C．best | D．better |
Let’s go to ______ cinema – that’ll take your mind off the problem for _____while.
| A．the; the | B．the; a | C．a; the | D．a; a |