______ in the queue for half an hour, the old man suddenly realized he had left the check in the car.
| A．Waiting | B．To wait |
| C．Having waited | D．To have waited |
Many parents __________ challenging conversations with their children later this month to help them recover from the panic.
| A．have had | B．will be having | C．have | D．will have had |
It is not the strongest of the species that survives, nor the most intelligent that survives. It is______ that is most adaptable to change.
| A．one | B．that | C．the one | D．this |
_______ application of transgenic technology（转基因技术）should be restricted on all food production and the government should take _______ “scientific attitude” toward genetically modified food.
| A．The ; a | B．An; the | C．The; the | D．An; a |
The little boy talked his mother ______buying him a home computer.
| A．of | B．over | C．to | D．into |
---What do you think of the old couple?
-----It was an act of _____that they distributed food among the homeless.
| A． hardship | B． psychology | C． routine | D．mercy |