(1) He would tell me if he (knows / knew / known ) the fact.
He would tell me if he [knew] the fact.
He would have told me if he [had known] the fact.
He will tell me if he [knows] the fact.

(2) If she (calls / called / had called ) me, I wouldn't have had to wait that long.
If she [had called] me, I wouldn't have had to wait that long.
If she [called] me, I wouldn't have to wait that long.
If she [calls] me, I don't/won't have to wait that long.

(3) She has a high fever. If she (goes / went / gone) to work, her condition would get
She has a high fever. If she [went] to work, her condition would get worse.
She has a high fever. If she [goes] to work, her condition will/may get worse.
She had a high fever. If she [had gone] to work, her condition would have gotten worse.

(4) If I ( have / had / had had ) more courage, I would have asked her to marry me.
If I [had had] more courage, I would have asked her to marry me.
If I [had] more courage, I would ask her to marry me.
If I [have] more courage, I will ask her to marry me.