题目

认真阅读下面的图表与文字，并按照要求用英语写一篇150词左右的文章。 Significant numbers of high school students are receiving additional assistance from tutors. That requires a measure of time, commitment and sometimes a lot of money. Tutors may be good for improving test scores, but they may harm a lot if students become overly dependent on tutors. Tutors' role should be one of assessment, monitoring and assistance, not to take over and perfect. Tutors may be used to bridge the gap, but the responsibility stays on the student to take an active role in mastering th原子序数为94的钚（Pu）是一种核原料，该原子的质子数和中子数之和为239，下列关于该原子的说法正确的是（　　）A．中子数为94B．核外电子数为94C．质子数为94D．核电荷数为239