reciprocate|reciprocated|reciprocates

两国决定互相给予签证优惠。

The two countries decided to ___reciprocate visa benefits.

他用一份礼物回报了她的帮助。

He ___reciprocated her help with a gift.

锯子在木板上往复移动来切割木材。

The saw ___reciprocates back and forth to cut through the wood.