已知５％氨水的密度为ρ1g/ml，25%氨水的密度为ρ2g/ml，ρ1>ρ2，若将上述两溶液等体积混合，所得氨水溶液的质量分数是（ ）
| A．等于15% | B．大于15% | C．小于15% | D．无法估计 |
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 |
It’s high time you had your hair cut ; it’s getting _______ . 
| A．too much long | B．much too long |
C．long too much | D．too long much |
My friend showed me round the town, ______ was very kind of him. 
| A．which | B．that | C．where | D．it |