Bill was doing a lot of physical exercise to build up his .A. abilityB. forceC. motivatio

问题补充：

Bill was doing a lot of physical exercise to build up his .

A. ability

B. force

C. motivation

D. strength

答案：

A. ability

B. force

C. motivation

(答案→)D. strength

解析：词义辨析。A. 能力；才能 B.武力；力量 C. 动机 D.力气；强度。句意：比尔做了大量体育锻炼在增强他的力气。故选D。