测定游离二氧化硅含量时的采样方法有两种：其中一种是在（）采集自然沉降尘。

A.设备上

B.呼吸带

C.底板处

D.煤壁处

The task at hand now is to (56) the programmers who still use yesterday’s software technology to solve today’s software problems. Object-oriented programming requires a new attitude toward problem (57) . Problem (57) with computer system becomes more natural. Application can (58) be translated into (59) . Although it is commonly believed that it will be easier to train new programmers to use object-oriented techniques than to (60) programmers who have substantial experience in applying conventional programming language constructs.

A．solve

B．solves

C．solved

D．solving