问题补充：
Soon she swim a quarter of a mile.
A. can
B. could
C. is able to
D. will be able to
答案：
A. can
B. could
C. is able to
(答案→)D. will be able to
解析：can能，能够；could， can的过去式；is able to能够；will be able to能够。句意：不就她就能游四分之一公里了。结合语境可知本句描述的是将来的动作，故用一般将来时态，选D。
