Even if you are an experienced teacher, you sometimes ____ make some mistakes.
A. can B. must 
. should D. will
The USA is a large country in ________ many different dialects are spoken.
| A．that | B．which | C．where | D．it |
Look at this! It’s broken now! You ________ have been careful!
| A．could | B．must | C．would | D．should |
It was my sister ________ first had the idea to cycle along the entire Mekong River.
| A．who | B．whom | C．/ | D．which |
I’m surprised to hear from my school teacher again. ________, it is ten years since we met last.
| A．In a word | B．Believe it or not | C．That’s to say | D．Of course |
My classmates insisted that I ________ the school field trip to Jilin.
| A．organized | B．would organize | C．organize | D．had organize |