[填空题]
The Eiffel Tower (Fig. 13–29) is built of wrought iron approximateln ,gz)pki 6jf tp9or,)y 300 m te1 yf.f ap+ q1nf1 hw31g5 68lmvhgyuaall. Estimate how mu11fyega.afvh1q 51 l8m+3f gunhwp6ych its height changes between July (average temperature of 25°C) and January (average temperature of 2 $^{\circ} $ C). Ignore the angles of the iron beams, and treat the tower as a vertical beam. m