In the past decades, sea ice ______ in the Arctic as a result of global warming.
| A．had melted | B．has been melting | C．melted | D．is melting |
That was a terrible night . The rain was pouring down, _________ thunder and lightning.
| A．being accompanied by | B．accompanied by | C．accompanying | D．accompanies |
The bus hit against a tree in the fog and __________to the deep valley, with ten passengers killed and twenty wounded.
| A．down did it roll | B．down rolled it | C．down it rolled | D．it down rolled |
Understanding the cultural habits of another nation, especially ____________ containing as many different subcultures as the United States, is very difficult.
| A．one | B．that | C．some | D．the one |
As we all know, apples are sold by ____ weight, and socks are sold by _______dozen.
| A．the; a | B．/; a | C．/; the | D．the; the |
Many difficulties have ______ as a result of the changeover to a new type of fuel.
| A．risen | B．arisen | C．raised | D．arose |