Radium salts，which have been found to ______ in bones，give rise to bone cancer.
| A．pile up | B．build up | C．keep up | D．pull up |
I remember the time _____ Eric won that speech competition.
A where B why C when D which
You like travelling, _____ you?
A don’t B won’t C didn’t D haven’t
Jack, _____ friend, went back to America last Monday.
A me B I C my D mine
— My bike is broken. _____ I use yours?
— Sure. Here it is.
A Must B Will C Should D May
Both cities ____very beautiful, attracting people from all over the country.
A has B have C are D is