if I..... a word, I look it up in my dictionary
a. doesn't know b. not know c. don't know
I'm sure Sue would understand if you.... the situation
a. explain b. explained c. explains
we will go to the beach if the weather is good
a. first conditional b. second conditional c. zero conditional
if we told them the truth, they...... us
a. believed b. will believe c. would believe
if we.... Bill to the party, we would have to invite his
a. invited b. invite c. invites