每空一詞他們今天下午4點(diǎn)到達(dá)北京.They ______ ______ arrive in Beijing at 4 o'clock this afternoon.

熱心網(wǎng)友

are to be to 表示預(yù)計(jì)/安排之中的事情

熱心網(wǎng)友

They __are__ __to__ arrive in Beijing at 4 o'clock this afternoon.

熱心網(wǎng)友

are to