以下构成一致行动人的有（）

A.投资者之间存在合作关系

B.甲公司的董事在乙公司当总经理，甲乙为一致行动人

C.持有投资者5%股份自然人股东的直系亲属

D.甲公司的监事在乙公司担任董事

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.

（57）是（）

A.solve

B.solves

C.solved

D.solving