As much of the item as possible should be included in the stem. Don't load the stem down with irrelevant material. Use negatives or double negatives sparingly in the question or stem. Beware of providing irrelevant grammatical cues. These are variation of the same thing.
Numerical problems are short answer items.
The following suggestions should aid you in writing effective completion or short answer items. Don't leave too many blanks in a statement. Put blanks at the end rather than at the beginning of an item. Omit only key words for completion. In numerical problems indicate the type of units in which the answer is to be expressed if it doesn't give clues to the answer.