Lest
S:Sub+(aux.v.)+principal verb+..(n/adj./adv)+lest+sub(2)+should/might+base form of principal verb+…
Ex:He walks fast lest he should miss the train.

Would that
S:Would that+sub+could+be/base form of principal verb+…+n+..
Ex:Would that I could visit Tajmahal.

If
(a)If+sub+present form of principal verb+..n/adj./adv.+sub(2)+can/may/shall/will+base form of principal verb+..(n)
Ex:If you work hard,you will prosper in life.

(b)If +sub+past form of principal verb+..n/adj./adv.+sub(2)+could/would/might+base form of principal verb+…(n)
Ex:If you studied hard,you could pass in the exam.

(c)If+sub+were+…+n+sub(2)+could/would/might+base form of principal verb+…n/sub(2)+could/would/might+have+past participle form of principal verb+…n.
Ex:a.If I were a bird,I could fly in the sky.
b.If I were a bird,I could have flown in the sky.

(d)If+sub+had+past participle form of principal verb+…n/adj./adv.+sub(2)+could/would/might+have+past participle form of principal verb+….n
Ex:If I had finished the work timely,I would have left the place.

Had
S:Had+sub+been/past participle form of principal verb+..n+sub(2)+would/could/might+have+past participle form of principal verb+…n
Ex:Had I been a king,I could have helped the poor.

Md. Rafiqunnabi, Lecturer, English, Govt. Mujibur Rahman Women’s College, Bogura.