( )是衡量保温材料及制品的保温性能的重要标志。

A．材料的吸水率

B．导热系数

C．吸湿率

D．含水率

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.

（59）是（）

A.classes

B.class

C.objects

D.object