Dear Mohamed Mostafa,
Sorry for my late reply. You can check the answer of your quizes in the quiz page itself. Whenever you submit a wrong answer to the quiz you will find a mark on this question.
Regarding the floats, i mean here the schedule floats, whoever use it first own it unless otherwise mentioned in the contract. For example, if the client delayed the approval of certain material, and this material has a float, the contractor cannot claim for extension of time because of this delay since it has a float it the schedule. In the other hand, if the contractor delayed an activity within the floats, the client cannot involve further dalys that exceeds the total floats since the contractor burned the floats first.