健康人血液的pH总是维持在7.35～7.45之间，这是由于
| A．人体内含有大量水分 |
| B．血液中NaCl的含量保持恒定不变 |
| C．血液中有许多对酸碱度起缓冲作用的物质 |
| D．血液中HCO3-和H2CO3的浓度比保持恒定 |
According to scientists, our mental abilities begin to __________ from the age of 27 after reaching the highest level at 22.
| A．differ | B．shrink | C．fail | D．decline |
The Well Hotel stands in a quiet place_______ the main road at the far end of the lake.
| A．to | B．for | C．off | D．out |
Don’t defend him any more. It’s obvious that he _________ destroyed the fence of the garden even without apology.
| A．accidentally | B．carelessly |
| C．deliberately | D．clumsily |
It may not be a great suggestion. But before ______ is put forward, we’ll make do with it.
| A．a good one | B．a better one |
| C．the best one | D．a best one |
Studying Wendy’s menu, I found that many of the items aresimilar to _______ McDonald’s.
| A．those | B．ones | C．any | D．all |