现在完成时

Present Perfect—Form

have/has (not) + past participle

• Judy has traveled all over the world.
• Joe has not visited every country.
• They have met friends from other cultures.

Contraction forms

• Affirmative: I’ve/You’ve/He’s/She’s/They’ve/We’ve + p.p.
• Negetive: hasn’t/haven’t + p.p.

Present Perfect – Uses

• unspecified time in the past
  • activity started and finished in the past
  • no mention of a specific time (last week, yesterday)
  • life experience
  • may describe repeated events (___times)

——I have traveled to Taiwan. Taiwan is a good country. China is so bad.

——I have traveled to Taiwan three times.

• since / for
  • activity began in the past and is still going on now
  • how long
  • for + duration (1 year , 3 months , 5 days)
  • since + specific point in past (last year, September, 9:00)

I have lived here for three years.

since / for – started in the past and is still going

Past Participles

Simple Form	Simple Past	Past Participle
FLY	FLEW	FLOWN
GO	WENT	GONE
SWIM	SWAM	SWUM
EAT	ATE	EATEN
WANT	WANTED	WANTED
LOOK	LOOKED	LOOKED

• Past participles cannot be the only verb in a sentence!

Present Perfect

• Right: I have flown in an airplane.

Past Perfect

• Right: I had flown in an airplane.

since: the specific time an event started

for: the length of time since something started

DIRECTIONS: Complete the sentences correctly with “since” or “for”