21.   Children frequently do not heed warning signals of overheating and dehydration and tend to drink only when thirsty, which is not adequate.

22.   Chrysler Corp. is sending a warning signal to plaintiff lawyers who have mired it in class-action lawsuits that the carmaker considers frivolous.

23.   Federal investigators said late on Thursday that traffic lights and warning signals had been malfunctioning at the railroad crossing.

24.   Federal investigators said Thursday that traffic lights and warning signals had been malfunctioning at the railroad crossing where a commuter train hit a school bus on Wednesday.

25.   For his part, Rubin told reporters recently that the warning signals, while evident, did not suggest the size of the problem on the horizon.

26.   For investors, though, such a proliferation should be a warning signal, said John Rekenthaler, director of research for Morningstar.

27.   For Kissinger, the Pinochet case was a warning signal of the dangers that could emerge as the concept of universal jurisdiction gains strength.

28.   Harris said that despite all the warning signals, he never even considered that he might have prostate cancer.

29.   He mimicked to perfection the Doppler effect of warning signals rushing by as we headed north.

30.   Heed the warning signals.