Samuel Clemens , ______ Mark Twain , became a famous writer .
| A．was known as | B．known as | C．was known for | D．known for |
You and I could hardly work together, _____ ?
| A．could you | B．couldn’t I | C．couldn’t we | D．could we |
Please do me a favor — ______ my friend Mr. Smith to Youth Theater at 7:30 tonight.
| A．to invite | B．inviting | C．invite | D．invited |
— It’s the office! So you ______know eating is not allowed here.
— Oh, sorry.
| A．must | B．will | C．may | D．need |
Nowadays people sometimes separate their waste to make it easier for it ______. .
| A．reusing | B．reused | C．reuses | D．to be reused |
She is very dear to us. We have been prepared to do ______ it takes to save her life.
| A．whichever | B．however | C．whatever | D．whoever |