6. ---What _______ is the most helpful invention?

　 ---I think the most helpful invention is the computer.

　 A. you think B. I think

　 C. do you think D. you do think

5. While she was walking along the road, she ________ that those red leaves had something yellow inside.

　 A. looked B. knew C. heard D. noticed

4. ---When will you leave?

　 ---I won’t go _______ he comes back.

　 A. until B. while C. when D. why

3. ---Who _______ the battery-operated slippers invented ______?

　 ---Julie Thompson, I think.

　 A. was; to B. was; for C. were; by D. were; with

2. The number of teachers in our school _______60 and a number of them _______ women teachers.

　 A. is; are B. are; is C. am; are D. be; are

1. Computers can be used _______ sending e-mails.

　 A. as B. for C. to D. by

5. A chef _______(call) George Crum invented potato chips.

4. The house is full of ________ (wood) furniture.

2. The light bulb is one of Edison’s ____________(invent).

3 We had a_____________(please) evening at Susan’s home.

1. The ____________(discover) of oil on their land made the family rich.