Here is another interactive exercise on linking words. You will be given a set of three linking words, and you must select the one that doesn't belong in the group. For example, if two of the words are used to add information, but the third word is used to contrast something, the third word is the one you should select - the odd man out, so to speak.
It's kind of like this, but with vocabulary :)
Each question contains a trio of linking words. Select the one that doesn't belong in the group.
C) Because doesn't belong as it is used to demonstrate cause. while however and but are used to indicate exception.
Before you attempt the exercise, why not review linking words / transitional devices here or here.