— 4 00 . . . /> .39 32 .36 .29 .34 25 31 .33 18 . 3 / .30 22 34 J7 “ls : '9 - 2 ' -1/ 300 . .35 .39 40 200 — l (pm) í 1 —I I • » 300 400 500 600 F/G. 2 268