Jack moved to Paris. He lost contact with most of his former friends, (complex sentence)
【正确答案】：After Jack moved to Paris,he lost contact with most of his former friends.
【题目解析】：本句的要求是将两个单句变成一个复合句（complex sentence）。我们可以将其变成一个时间状语从句
After Jack moved to Paris（在杰克搬到巴黎之后）。
