—Hello. Can I speak to Mr. Brown?
—I'm sorry, but it is 3 weeks ___ he worked here．
A．before B．since C．after D．while
—Hello. Can I speak to Mr. Brown?
—I'm sorry, but it is 3 weeks ___ he worked here．
A．before B．since C．after D．while
答案:B考查连词。
解析: “It’s +时间段 since+ 主语+一般过去时”为固定句式。语境为：他在这里工作已经有3个星期了。