小说的主题常常要通过（）来表现。
A、人物
B、情节
C、环境
D、结构
参考答案：B
We have to give the users something new ________ what we’ve already offered, which is the only way to broaden the appeal of the website.
A．regardless of
B．in addition to
C．in exchange for
D．according to
可持续发展包括哪三方面的涵义？
