This has become more difficult than it used to be owing to the extent and complexity of the specialized knowledge required of various kinds of technicians. (l. 3-5)
It has become more difficult than before because different kinds of technicians are required to specialize in more complex and wider range of kn
owledge today. 由于现在要求各类技术人员掌握的专业知识越 来越多，越来越复杂，要做到良好的比例意识 比以前更难了。