Mum won't let Simon go out unless he promises to be back ______ 10 o'clock tonight.( )
A.tillB.beforeC.asD.since
Eric often _________his aunt before he moved to the city.
has visited
visits
visited
Frank and his friends had great fun _________volleyball on the beach yesterday.
play
playing
to play
Although it is raining _________, the policemen are still on duty in the street.
clearly
directly
heavily
Mr. Huang is an excellent English teacher who has over 20 years' teaching _________.
experience
information
knowledge
Uncle Liang has a great collection of _________watches.
enjoyable
valuable
comfortable