单项选择题
A．do B．doing C．be doing D．having done
By（）your work environment and personal practices, you m...
单项选择题By（）your work environment and personal practices, you may be able to reduce fatigue and discomfort.
A．adapt B．having adapted C．adapting D．being adapted
The commercial purpose of a trade mark is（）the goods or...
单项选择题The commercial purpose of a trade mark is（）the goods or services of a company from those of competitors.
A．to distinguish B．having distinguished C．distinguishing D．being distinguished
Were it not for your help, I（）in trouble now. A．was B．w...
单项选择题Were it not for your help, I（）in trouble now.
A．was B．were C．had been D．would be
