【推荐1】All our officers are trained to defend themselves ________ knife attacks. (用适当的词填空)

【推荐1】It had been possible (but not easy) to buy single copies of newspapers before 1830, but this usually meant the reader had to go down to the printer’s office________(purchase) a copy. (所给词的适当形式填空)

【推荐2】We must take concrete measures______________ (strengthen) the flexible management. (所给词的适当形式填空)

【推荐3】_________(celebrate) the 70^th anniversary of the founding of the People’s Republic of China (PRC), President Xi jinping signed a presidential decree (总统令) on Sep.17 to award 42 individuals __________(vary) national honorary titles. (所给词的适当形式填空)

【推荐1】The sharks have evolved __________ (survive) in low-oxygen environments, enabling them to hunt during low tides. (所给词的适当形式填空)

【推荐2】He has made up his mind _____(overcome) his shortcomings. (所给词的适当形式填空)