【C17】A．InB．UponC．ByD．With

A．InB．OnC．ByD．At

【C9】A．inB．onC．byD．to

【C6】A．inB．toC．byD．for

This is a matter ____ some difficulty.A: inB: ofC: byD: for

【C12】A．inB．ofC．byD．for

【C17】A．onB．inC．byD．for