Complete the following passage by using the words in the box．Each word can only be used once．Note that there is one word more than you need.

A．primarily	B．similar	C．considerately	D．connections	E．instructed
F．series	G．personal	H．served	I．defined	J．environment

In a study of the university of Minnesota, twins (some raised together and others who had grown up apart) were tested for a wide range of personality traits (特征)．In terms of happiness－   as the ability to enjoy life－twins who are separated soon after birth were much less alike than twins raised together．But when it comes to unhappiness, the twins raised apart－some without contact for as long as 64 years－were as   as those who had grown up together.
Why is unhappiness less influenced by   ? When we are happy, we are more responsive to people and keep up better than when we are feeling sad．
This doesn’t mean, however, that some people are born to be sad and that’s that．Unhappiness may be related to genes, but this inherited trait can be influenced by   choice．You can increase your happiness through your own actions.
In a whole of experiments by psychologists John Reich and Alex Zautra at Arizona State University, they asked students to select their favorite activities from a list of everyday pleasures－things like going to a movie, talking with friends and playing cards.
Then the researchers  some of the students in the experiment to increase the number of favorite activities the participated in for one month (the participants in the study    as controls (对照组) and did not vary their activity level)．Result: Those who did more of the things they enjoyed were happier than those who didn’t．The conclusion, then, is that the pleasure we get from life is   ours to control.