Themissingboyswerelastseen________neartheriver.
A、playingA
所填的词为主语补足语，因其后有明确的地点，补足语表示动作当时正在进行中，所以只能使用 playing 。
As for family education, parents are encouraged to rely on ________ rather than punishment.
A well-known example of the large scale destruction of an ecosystem through vegetation removal to accommodate tourist facilities is the case of the _______.
This is ________ good reading habits are not only an important study skill for the student, but also an important life skill for anyone.
Which of the following country is not a member of OECD?
Tourist expenditures have different effects on a destination economy:sales by food vendors to restaurants are _______ effect;while taxi fares and airline ticket sales are _______ effect.
