`@Kem`
`+` Liên từ "for": `-`Those children have slept for 2 hours every afternoon
`-`We were kept waiting for three hours
`-`Lucy walked for three miles
`-`He asked me for some money
-Go for a walk.
`+` Liên từ "yet": `-`I haven’t completed my homework yet
`-`She hasn’t watched the episode yet
`-`He hasn’t phoned me back yet
`-`We have yet to determine if she is on board
`-`The price has yet to be announced