21.  A fresh blanket of snow makes it difficult to see exactly how wide a swath the Merced and its feeder creeks cut.

22.  A good teacher knows how to maintain discipline.

23.  A government commission is now investigating how these billions were made.

24.  A husband was given a crash course in how to deliver a baby by a midwife on the phone.

25.  A little girl playing the part of Mary was asked by the teacher to imagine how Mary would be feeling in the stables.

26.  A major problem is how to make the comparison groups as similar to the experimental group as possible.

27.  A man among men knows how to murder.

28.  A manual of advice on how best to forecast the demand for new rail services of various types will then be prepared.

29.  A mathematical function grades how different these suggestions are from the misspelling, and the nearest few are suggested.