That boy looks very unhappy．Let’s________．
| A．to cheer up him |
| B．to cheer him up |
| C．cheer him up |
| D．cheer up him |
His sister usually helps him________his homework．
| A．doing |
| B．do |
| C．does |
| D．to doing |
—Your tea smells great！
—It’s from India．Would you like________？
| A．it |
| B．this |
| C．some |
| D．little |
The World Health Organization has given some advice on________to protect us from being infected(感染)with H7N9．
| A．how |
| B．what |
| C．where |
| D．when |
—What do you usually help your mother________？
—I often do the dishes．
| A．to doing |
| B．to do |
| C．doing |
| D．does |