Measurements of the branching fractions for D ⁺ →K _S ⁰ K _S ⁰ K ⁺ ,K _S ⁰ K _S ⁰ π ⁺ and D ⁰ →K _S ⁰ K _S ⁰ ,K _S ⁰ K _S ⁰ K _S ⁰

By analyzing 2.93fb ⁻¹ of data taken at the ψ(3770) resonance peak with the BESIII detector, we measure the branching fractions for the hadronic decays D ⁺ →K _S ⁰ K _S ⁰ K ⁺ , D ⁺ →K _S ⁰ K _S ⁰ π ⁺ , D ⁰ →K _S ⁰ K _S ⁰ and D ⁰ →K _S ⁰ K _S ⁰ K _S ⁰ . They are determined to be B(D ⁺ →K _S ⁰ K _S ⁰ K ⁺ )=(2.54±0.05 _stat. ±0.12 _sys. )×10 ⁻³ , B(D ⁺ →K _S ⁰ K _S ⁰ π ⁺ )=(2.70±0.05 _stat. ±0.12 _sys. )×10 ⁻³ , B(D ⁰ →K _S ⁰ K _S ⁰ )=(1.67±0.11 _stat. ±0.11 _sys. )×10 ⁻⁴ and B(D ⁰ →K _S ⁰ K _S ⁰ K _S ⁰ )=(7.21±0.33 _stat. ±0.44 _sys. )×10 ⁻⁴ , where the second one is measured for the first time and the others are measured with significantly improved precision over the previous measurements.