(2013·福建高考)________basic first?aid techniques will help you respond quickly to emergencies.

A．Known B．Having known

C．Knowing D．Being known

(2012·浙江高考)No matter how bright a talker you are, there are times when it's better ________ silent.

A．remain B．be remaining

C．having remained D．to remain

(2011·上海高考)It's no use ________ without taking any action.

A．complain B．complaining

C．being complained D．to be complained

(2013·重庆高考)The engine just won't start.Something seems ________ wrong with it.

A．to go B．to have gone

C．going D．having gone

(2011·上海高考)Today we have chat rooms, text messaging, emailing ... but we seem ________ the art of communicating face?to?face.

A．losing B．to be losing

C．to be lost D．having lost

(2010·福建高考)In April, thousands of holidaymakers remained ________ abroad due to the volcanic ash cloud.

A．sticking B．stuck

C．to be stuck D．to have stuck

(2013·河南省普通高中适应性检测卷一)People spend many years learning about favorite sports and ________ how to do them well.

A．practice B ．practiced

C．practicing D．to practice

(2013·威海两校模拟)________ the earth to be flat, many feared that Columbus would fall off the edge of the earth.

A．Having believed B．Believing

C．Believed D．To believe

(2013·四川省泸州市4月模拟)There was no signal in that faraway village and all my attempts ________ you failed.

A．to contact B．contacting

C．contacted D．having contacted

(2013·河南豫西五校质量检测)The text is too difficult. The explanation of our teacher will help make it easy ________.

A．to understand B．to be understood

C．understood D．understanding