$2-2$

$2-2$A$$

B $$A $$

$M_0$ A $$ C $$

$R_{A}EIl$

$$

$(1)M_0,R_A,EI,l,x$

$M$

$F$

$(2)M_0,EI,l,$

$2-2$

$R_A.$

$.$