It was the last day of the final exam in a college. On the steps of building, a group of engineering students were waiting for the last exam. On their faces was confidence（自信的）. 
    They knew the exam would be easy. The professor (a teacher at a college) had said they could bring any books or notes during the test.
Right after they came into the classroom. The professor handed out the papers. There were only five questions on it.
    Three hours passed. Then the professor began to collect the papers. The students no longer looked confident. On their faces was nervous expression（表情）. The professor watched the worried faces before him, and then asked, “How many of you have finished all five questions?” No hand was raised. “How many of you have answered four?” Still no hands. “Three? Two?” The students moved restlessly in their seats.    “One, then? Certainly somebody has finished one.” But the class kept silent. The professor said, “That is exactly what I expected. I just want to make you know clearly that even though you have completed four years of engineering. There are still many things about the subject you don't know. These questions you could not answer are common in everyday practice.” Then, smiling, he added, “You will all pass this course, your education has just begun.”
    The years have obscured the name of this professor, but not the lesson he taught.

一个化肥厂原计划14天完成一项任务，由于每天多生产化肥3.5吨，结果9天就完成任务．原计划每天生产化肥____ 吨．

古人云：“近朱者赤，近墨者黑。”这句话表明（    ）          

①广交朋友，朋友多是好事                        ②朋友之间是相互影响的 

③结交好的朋友，会使我们终身受益           ④结交坏的朋友，会使我们染上坏思想、坏习惯