如图，在平面直角坐标系中，直线\({l_1}:y = \frac{1}{2}x\)与直线\({l_2}\)交点\(A\)的横坐标为2，将直线\({l_1}\)沿\(y\)轴向下平移4个单位长度，得到直线\({l_3}\)，直线\({l_3}\)与\(y\)轴交于点\(B\)，与直线\({l_2}\)交于点\(C\)，点\(C\)的纵坐标为\( - 2\)．直线\({l_2}\)与\(y\)轴交于点\(D\)．