un·der·laid /ˌʌndɚ/
  underlay過去式和過去分詞
  Un·der·laid a. Laid or placed underneath; also, having something laid or lying underneath.
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  underlay
       See underlie
       [also: underlaid]
  underlay
       n : a pad placed under a carpet [syn: carpet pad, rug pad, underlayment]
       v 1: raise or support (the level of printing) by inserting a
            piece of paper or cardboard under the type; "underlay
            the plate"
       2: put (something) under or beneath; "They underlaid athe
          shingles with roofing paper"
       3: provide with a base, support, lining, or backing; "underlay
          the boards with joists"
       [also: underlaid]