急問一d英文tense 問題

At 9:30 am., you can also respond to a question of "why the dishes are still dirty?" by saying:

Mary just washed the dishes for fun. She wasn't serious.

(~ washed the dishes just for fun; just = only)

早上九點半可以講：

1. (you express your feeling)
Mary has just washed the dishes. It is strange that the dishes got dirty again.

Tense: present perfect


2. (you respond to the question "where is Mary?")
Mary just finished washing the dishes half an hour ago and already left.

Tense: simple past with time reference

The present perfect continuous:-
Mary has been washing dishes for (9-8=1)hr.
Mary has been washng since 9am.
Mary has washed dishes for 1 hr.---present perfect tense
In subordinate clause of Time or Condition expressing an action in the present tense:-
If dishes go dirty Mary will wash (=will have to wash) dishes again.

NO, You Can Write Say" Mary Have to wash dishes again, because its looks dirty here!!"