问题
单项选择题
Stamp collection has long been recognized as having an educational value. There is every reason to encourage young people to take an interest in them, thereby ______ to their knowledge of geography and history.
A．to add
B．adding
C．added
D．adds
答案
参考答案：B
解析：thereby“因此”，接分词短语表示结果。thus, hence, therefore都有同样的接续用法。