$(1)\,\,{{(C{{H}_{3}})}_{3}}\bar{\ddot{C}}$
$(2)\,\,{{(C{{H}_{3}})}_{2}}\bar{\ddot{C}}$
$\,(3)\,\,C{{H}_{3}}\bar{\ddot{C}}{{H}_{2}}$
$(4)\,\,{{C}_{6}}{{H}_{5}}\bar{\ddot{C}}{{H}_{2}}$