In a refinery, the capacity of oil tank A is 70 per cent of the capacity of oil tank B.
How many more gallons of oil are in tank A than in tank B （）
(1)Tank A is 90 percent full; tank B is 50 percent full.
(2)When full, tank A contains 50,000 gallons of oil.
A.条件（1）充分，但条件（2）不充分.
B.条件（2）充分，但条件（1）不充分.
C.条件（1）和（2）单独都不充分，但条件（1）和条件（2）联合起来充分.
D.条件（1）充分，条件（2）也充分.
E.条件（1）和条件（2）单独都不充分，条件（1）和条件（2）联合起来也不充分.
