问题
选择题
After Jack had sent some e-mails, he _______ working on his project. [ ]
A. had started
B. has started
C. started
D. starts
答案
答案：C
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After Jack had sent some e-mails, he _______ working on his project. [ ]
A. had started
B. has started
C. started
D. starts
答案：C