[填空题]
For the system of Fig. 4-32 gn r.j2chm3i6(Ex3ot2d7 oiltdv19*5hljk qa9;ap ul )fs 8kk m+ample 4-20) how large a mass would box A have to have to preuiqo1h 7dk3dsmkt *alftv;l)p5l 9 o 9a+82jkvent any motion from occurring? Assume $\mu_{\mathrm{s}}=0.30$ .
