【单选题】

How many different kinds of emotions do you feel You may be (1) to find that it is very hard to specify all of them. Not only (2) hard to describe in words, they are difficult to (3) .As a result, two people rarely (4) all of them. However, there are a number of (5) emotions that most people experience.

When we receive something that we want, or something happens (6) we like, we usually feel joy or happiness. Joy is a positive and powerful emotion, (7) for which we all strive. It is natural to want to be happy, and all of us (8) happiness.As a general (9) , joy occurs when we reach a (10) goal or obtain a desired object.
(11) people often desire different goals and objects, it is (12) that one person may find joy in repairing an automobile, (13) another may find joy in solving a math problem. Of course, we often share (14) goals or interests, and therefore we can experience joy together. This may be in sports, in the arts, in learning, in raising a family, or in (15) being together.
When we have difficulty (16) desired objects or reaching desired goals we experience (17) emotions such as anger and grief. When little things get in our way, we experience (18) frustrations or tensions. For example, if you are dressing to go out (19) a date, you may feel frustration when a zipper breaks or a button falls off. The more difficulty you have in reaching a goal, the more frustrated you may feel and the more angry you may become. If you really want something to happen, and you feel it (20) happen, but someone or something stops it, you may become quite angry.
A、if B、what
C、that
D、when