If you swim in a river or lake, be sure to investigate is below the water surface. Often there are rocks or branched hidden in the water.
| A．what | B．who | C．that | D．whoever |
_____ new cure for this disease that medical experts have recently developed proves to be ______ most effective, although it can not completely kill all the viruses.
| A．A; a | B．The; / | C．/; the | D．A; the |
— What do you think of the novel written by the well-known writer?
— Sorry, no _________!
| A．wonder | B．doubt | C．comment | D．way |
If my father ______ here yesterday, he would have stopped me from going surfing.
| A．had been | B．were | C．should be | D．has been |
In my opinion, we need to begin ______ we stopped yesterday to ensure we won’t miss anything.
| A．when | B．where | C．how | D．what |
Steve Jobs’ success in digital field proved ______ it took to be a best CEO.
| A．what | B．which | C．that | D．how |