听下面一段独白,请根据所听内容回答四个问题。
(I)当 a=1 时,求 f(x)≥|x+1|+1 的解集;
(II)若不等式 f(x)+3x≤0 的解集包含 {x|x≤−1} ,求 a 的取值范围.
Some children prefer to eat junk food ________ it's not good for their health.