John helped me write a letter __English. A. with B. of O c.in O D. by

问答题lf a product configuration isspecified and then examined to determine whether the performancerequirements are met. A. finally B. tentatively C. temporary D. have been

问答题The maximum allowable deflection of a shaft­____determined by critical speed, gear, or bearing A. often B. must )C. was D. is usually