The missing boys were last seen ________ near the river.
A、playingA
所填的詞為主語補足語，因其后有明確的地點，補足語表示動作當時正在進行中，所以只能使用playing。
Touristexpenditureshavedifferenteffectsonadestinationeconomy:salesbyfoodvendorstorestaurantsare_______effect;whiletaxifaresandairlineticketsalesare_______effect.
The Netherlands is the only country in Europe which permits euthanasia, ________ it is not technically legal there.
Themissingboyswerelastseen________neartheriver.
______ a little earlier, I would have caught the train.
______ are the primary destinations for the Chinese at present.
