______ you may have , you should gather your courage to face the challenge .
| A．However serious a problem | B．Whatever serious a problem |
| C．However a serious problem | D．No matter how a serious problem |
I have no doubt in my mind______ they will be glad to see me.
| A．if | B．whether | C．that | D．about |
Eric received training in computer for one year, _______ he found a job in a big company.
| A．after that | B．after it | C．after which | D．after this |
With the help of high technology, many new substances（物质）______in the past years.
| A．discovered | B．have discovered | C．had been discovered | D．have been discovered |
______ is know to us all, good friends ______ happiness and value to our life.
| A．It; add | B．As; add up | C．It; add up | D．As; add |
Letterboxes are mu
ch more _______ in the UK than in the US, where most people have a mailbox instead.
| A．common | B．ordinary | C．normal | D．usual |