HI! LET ME GIVE U SOME GENERAL INFORMATION.WHEN THE DIFFERENCE IN THE ELECTRONEGATIVES OF THE TWO COMBINING ATOMS IS LESS THAN 1.7 COVALENT BOND IS FORMED. IN CASE OF ALCL3, E.N. OF AL=1.61 E.N. OF CL=3.16 DIFFERENCE=1.55. HENCE COVALENT. IN CASE OF BeCL2, E.N. OF AL=1.57 E.N. OF CL=3.16 DIFFERENCE=1.59. HENCE COVALENT. IF THIS ANSWERS TO UR QUESTION DO SEND A REPLY.. PLEASE NOTE: THE FIGURES ABOVE ARE PAULING ELECTRONEGATIVITY VALUES. ALSO THIS IS THE SIMPLEST WAY TO ANSWER UR QUESTION.