They plan _____ （have）a big party to celebrat their daughter's thirteenth birthday.
问题描述：
They plan _____ （have）a big party to celebrat their daughter's thirteenth birthday.
答
They plan __to have___ （have）a big party to celebrat their daughter's thirteenth birthday.
这里的知识点：plan to do sth 计划去做某事
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答
to have。plan to do sth.
答
to have
plan to do 计划做某事
他们打算为庆祝女儿十三岁生日开个大party