By the time Jack returned home from England，his son ________ from college.(2011·辽宁)
| A．graduated | B．has graduated |
| C．had been graduating | D．had graduated |
31．—Bob! How’s your project? I heard you started it last Friday，right?
—Oh！I _________for it．But I haven’t decided when to do it．
| A．have prepared | B．had prepared | C．have been preparing | D．was preparing |
30．__________a diary every day and you’ll improve your writing．
| A．Keeping | B．To keep | C．Keep | D．If you keep |
29．If we had taken such effective measures much earlier, the fiver__________so seriously now.
| A．is not polluted | B．would not be polluted |
| C．had not been polluted | D．would not have been polluted |
28．Thousands of Haitians cheered as the Chinese medical team arrived，many of________even
cried with joy.
| A．those | B．them | C．wh om |
D．Who |
27．—Our women athletes achieved great success in the Vancouver Olympic Winter Games．
—Yes No one could perform_________, I think．
| A．well | B．better | C．best | D．the best |