It never occurred to humans until the mid-1990s ______ some animals can be cloned.
| A．where | B．that | C．when | D．what |
Linda had her luggage________ an hour before her plane left.
| A．check | B．checking | C．to check | D．checked |
Could you drive me to the bookstore at noon if________?
| A．it's convenient of you | B．you are convenient |
| C．it's convenient to you | D．you will be convenient |
In my opinion, it's the flying birds rather than the pilot that________for the air crash.
| A．are to blame | B．is to blame | C．is to be blamed | D．are to be blamed |
The teacher didn't like ______composition written by the new student because it didn't make
_______ sense.
| A． the;a | B．the;/ | C．a; t he | D．a;／ |
_______ I see the photo,1 will always think of Mr Li, who once was very strict with us.
| A．Now that | B．Even though | C．The first time | D．Every time |