他看着服务员在给他准备一杯茶 He ______ the waiter _______ _______ a cup of tea for him.
问题描述：
他看着服务员在给他准备一杯茶 He ______ the waiter _______ _______ a cup of tea for him.
答
填saw,was preparing
或者一般现在时sees,is preparing
see后面引导宾语从句