21.   The mourning period lasted until the eyebrows grew back.

22.   The period of martial law lasted for seven months.

23.   The peak season for hepatitis A in Hong Kong is between February and June and the incubation period lasts from one to six weeks.

24.   The Serbs want the period to last several years.

25.   The U.S. letter apparently is part of U.S. assurances to the Palestinians that the interim period will not last indefinitely.

26.   The incubation period lasts up to three weeks.