“they are wasting resources, for example, time, energy and money.”
上面这句话不错，只是转折词“for example”不妥当；应该这样：
“they are wasting resources. for example, they use too much time, energy and money.”
不然就要换一换转折词，改用“such as”或“like”：
“they are wasting resources, such as (or like) time, energy and money.”
不管任何语言，转折词（transitional words）都扮演着一个重要角色，就是：承先启后，使句子紧凑，段落相吸，对文章结构，有良性作用。但是有些人几乎没有采用转折词的习惯，结果文句松散，上下文七零八乱，应该避免。
现在把主要转折词，分类列下，供大家参考。
ⅰ表示“尤有进者”的意思：
again, also, then, besides, further, furthermore, moreover, next, in addition等，如：
① jason teaches diligently. besides, he writes a lot.
② english is a useful language. for one thing, it is an official language in the un. then, it is widely used in business, science and technology.
ⅱ表示“反意见”：