“人要学会走路，也得学会摔跤，而且只有经过摔跤才能学会走路。”马克思的这一名言说明的道理是

A．挫折是财富，挫折越多越好

B．失败乃成功之母

C．遇到了挫折，要学会自我疏导

D．经历挫折的人肯定能成功

If you just spend your time _____ gains and losses, maybe you'll get nothing in the end. [ ]

A. checking

B. weighing

C. balancing

D. examining