The computer system suddenly when I was surfing the internet.
A, broke down B, broke up C, broke out D, broke in
This job needs ______ patience and practice, after all, it will become ______ enjoyable experience after weeks.
| A．/ ; the | B．the ; the | C．/ ; an | D．the ；a |
They ______ the train to Beijing．Otherwise, they would have returned home．
| A．need have caught | B．must have caught |
| C．must catch | D．may catch |
His father was the first on the farm ______ against the slave owner．
| A．fought | B．fighting | C．to fight | D．having fought |
As we all know, eating too much fat can ______ heart disease and cause high blood pressure.
| A．add to | B．attend to | C．contribute to | D．apply to |
I am so tired．_____ I could take the day off tomorrow．
| A．Only if | B．If only | C．Only too | D．What if |