翻譯 (from 中文 to 英文) very simple~

香港人講拉curve只是中英並用的口語法，用英文來說，不會用數學上的curve來形容成績(或評級，即Grades) 的分佈。拉curve是將評級按比例地分配，所以英文是
The school certificate examination results are on pro-rata basis.
要講清楚些是:
The allocation of grades in the school certficate examination is on pro-rata basis.

會考成績是拉curve計
The area-wide student examination result pulls the curve idea

According to HKCEE report, it follow calculating all curve

會考成績是拉curve計 :
Result of HKCEE is on a percentage basis using the curving formula.