正常的变化形式:

breaks breaking, buys buying, eats eating, falls falling, feeds feeding, finds finding, holds holding, keeps keeping, meets meeting, reads reading, says saying,

单三加es的:

catches, catching, does doing, teaches, teaching, goes going,

现在分词去e,加ing的:

comes coming, gives giving, makes making, shakes shaking,

现在分词最后字母重复的:

gets getting, runs running, shuts shutting, sits sitting,

单三形式特殊的:

has having,

go的三单是：goes