Dr. Frank failed many times but he finally _____ to find a successful way to solve the problem.
| A．broke off | B．broke up | C．broke down | D．broke through |
WalMart，the world's largest retailer(零售商)，sells in three months ________ the numbertwo retailer Home Depot sells in a year.
| A．that | B．which | C．when | D．what |
Professor Tang didn't give us a speech today.It was ________ he had a traffic accident on the way to school.
| A．that | B．when | C．why | D．because |
He taught his father how to get to know ________ is going on in his university life on the Internet.
| A．how | B．that | C．what | D．which |
It is obvious ________ the former Libyan government will be replaced with the opposition government.
| A．who | B．where | C．which | D．that |
When we arrived in ________ used to be called the foggy capital，we found London completely changed.London is now one of the capital cities in the world with the finest air quality.
| A．which | B．what | C．that | D．where |