e-commerce worries some merchants, it contributes to the development of delivery industries.
| A．When | B．Unless | C．While | D．Until |
Jack almost fell off the cliff, but managed to _____ until help came.
| A．keep on | B．catch on | C．count on | D．hang on |
The storm sweeping over this area now is sure to cause _____ of vegetables in the coming days.
| A．rarity | B．scarcity | C．invalidity | D．variety |
Don't _____ the news to the public until we give you the go-ahead (许可，准许).
| A．release | B．discard | C．relieve | D．retain |
If you _____ your demand, then maybe you will have more chance of getting what you want.
| A．conduct | B．dismiss | C．grant | D．moderate |
His _____of the aeroplane was correct in every detail and could really fly.
| A．shape | B．pattern | C．design | D．model |