20. T
T A
T TC
T A TC
Simple
Continuous
Perfect
Continuous
Perfect
FuturePast Present
write(s)wrote will write
did? do/does?
was/were am/is/are
writing
will be
writing writing
be + 4 (-ing)
written written
had have/has will havehave + 3 (-ed)
have been + 4 (-ing)
written
have/has beenhad been will have been
writing writing writing