There Can Be No Contract in the Following Examples

There can be no contract in the following examples:

A) An agreement to sell a company is subject to the buyer obtaining a government licence
B) A may sell his house to B on B obtaining a mortgage.
C) B must buy A's office block if a property survey is to the satisfaction of the bank lending B the money for the purchase
D) The contract states that B must buy A's land if B's solicitor is satisfied that A has title following a search of the Land Registry .