先要深入了解他 eat a peck of salt with a man before you trust him
深入 1.(达到事物的内部) go deep into; penetrate into 深入敌后 penetrate far behind enemy lines; 深入改革 deepen [intensify] the reform; further(ing) the reform; in-depth reform; 深入国境线 deep behind the frontier; 深入基层 go down to the grass-roots units; 深入实际 go deep into the realities of life; 深入地总结 sum up in a penetrating way; 深入体制改革 deepen the structural reform; 深入下层 go into the midst of the lower levels; 深入事物本质 probe; deeply into the essence of things2.(深刻) thorough; deepgoing 深入地分析 analyse in depth; 深入研究 study in a deepgoing way; 进行深入的调查研究 make a deep [thorough] investigation and study
了解 1.(知道得清楚) understand; comprehend; acquaintance 了解事物发展的规律 understand the laws of development of things; 一位优秀的教师必须了解儿童。 a good teacher must understand children. 你如果能正确和有效地使用一个字, 你就了解它了。 if you can use a word correctly and effectively, you comprehend it.2.(打听, 调查) find out; acquaint oneself with 了解国内外科学技术发展情况 keep abreast of current development in science and technology at home and abroad