语法填空
（1）Of the nineteen recognized polar bear subpopulations, three are declining, six ________ (be) stable, one is increasing, and nine lack enough data.
（2）While running regularly can’t make you live forever, the review says it ______ (be) more effective at lengthening life  65（than） walking, cycling or swimming.
（3）Fast food ________ (be) full of fat and salt; by eating (eat) more fast food people will get more salt and fat than they need in their diet.
（4）But at the moment, school ______(come) first. I don’t want to get too absorbed in modeling.