When writing intervals on the staff, it is common to confuse intervals with the same number of half steps.
（书写音程的时候，有时会将其半音的数目搞混）
For example, one may accidentally write C to F-sharp (an augmented fourth) instead of C to G-flat (a diminished fifth).
（比如，有人会把C到升F（增四度）写成C到降G（减五度））
Although both intervals sound the same and look identical on the keyboard, one is a fourth and the other is a fifth.
（尽管这两个音程听起来都一模一样，但一个是四度，另一个是五度）
Fortunately, an easy three-step process exists to reduce the risk of this mistake.
（还好，这种错误可以用一种“三步”的方法来避免）
Let's write a minor third from C.
（我们从C开始，写一个它的小三度）
First, write the generic interval on the staff. For this example, we will write a generic third.
（首先我们需要写一个通用音程。本例中我们用三度）
Next, figure out the number of half steps on the keyboard. Since a major third is 4 half steps, our minor third will be 3 half steps.
（然后算出键盘上半音的数量。因为大三度是四个半音，那么小三度就是三个半音）
Finally, compare the staff and keyboard results. Add any needed accidentals to the staff.
（最后比对一下五线谱上和钢琴键盘上的结果，在需要的地方添加变音记号即可）
C—E-flat is a minor third.
（C-降E是一个小三度） | 
For our next example, let's try a major sixth from F-sharp.
（接下来我们试一下升F的大六度）
First, write the generic sixth on the staff.
（首先写一个六度）
Next, figure out the half steps on the keyboard. A major sixth is 9 half steps.
（接下来算出键盘上的半音数。A的大六度有九个半音）
Finally, add any needed accidentals.
（最后加上需要的变音记号）
F-sharp—D-sharp is a major sixth.
（升F到升D是一个大六度） |
For our final example, we will write a diminished fifth from B.
（最后一个例子，我们来写一个B的减五度）
First, write the generic fifth on the staff.
（首先写一个五度）
Next, figure out the half steps on the keyboard. Since a perfect fifth is 7 half steps, our diminished fifth has 6.
（然后算出钢琴键盘上的半音数。纯五度有七个半音，所以减五度就有六个半音）
Finally, add any needed accidentals. In this example, no accidental is needed.
（最后加上需要的变音记号。在本例中不需要加变音记号）
B—F is a diminished fifth.
（B到F是一个减五度） |
Use this chart to reference the interval-writing process.
（下表是书写音程的顺序）