Unless _______ to speak, you should remain silent at the conference．

A．invited

B．inviting

C．being invited

D．having invited

Friendship is like money, easier made than _______．

A．kept

B．to be kept

C．keeping

D．being kept

Mr．Smith, _______ of the ________ speech, started to read a novel．

A．tired; boring

B．tiring; bored

C．tired; bored

D．tiring; boring

The research is so designed that once _______ nothing can be done to change it．

A．begins

B．having begun

C．beginning

D．begun

When _______, the museum will be open to the public next year．

A．completed

B．completing

C．being completed

D．to be completed

_______ in 1636, Harvard is one of the most famous universities in the United States．

A．Being founded

B．It was founded

C．Founded

D．Founding

The Olympic Games, _______ in 776B．C．, did not include women players until 1912．

A．first playing

B．to be first played

C．first played

D．to be first playing

Because of my poor English I'm afraid I can't make myself _______．

A．understand

B．to understand

C．understanding

D．understood

_______ more attention，the trees could have grown better．

A．Given

B．To give

C．Giving

D．Having given

Most of the artists who were _______ to the party were from South Africa．

A．invited

B．to invite

C．being invited

D．had been invited