English translation of '半吊子'

名

1. (指言行举止) blunderer
2. (指水平) incompetent
   ⇒ 半吊子的老师怎么能教出好学生呢？ (Bàndiàozi de lǎoshī zěnme néng jiāochū hǎo xuéshēng ne?) How can that incompetent of a teacher produce good students?
3. (指处事态度) good-for-nothing