現在進行時的基本用法：
a. 表示現在( 指說話人說話時) 正在發生的事情。
we are waiting for you.
b. 習慣進行：表示長期的或重複性的動作，說話時動作未必正在進行。
mr. green is writing another novel.
(說話時並未在寫，只處於寫作的狀態。)
she is learning piano under mr. smith.
c. 表示漸變的動詞有：get, grow, become, turn, run, go, begin等。
the leaves are turning red.
it's getting warmer and warmer.
d. 與always, constantly, forever 等詞連用，表示反覆發生的動作或持續存在的狀態，往往帶有說話人的主觀色彩。
you are always changing your mind.
典型例題
my dictionary ___, i have looked for it everywhere but still___ it.
a. has lost, don't find b. is missing, don't find c. has lost, haven't found d. is missing, haven't found.
答案d. 前句是一個仍在持續的狀態，套用進行時，由於沒有找到，其影響仍然存在，套用完成時，瞬間動詞用於否定式時可用於完成時。