钻石的折射率是（）。 A: 2.214 B: 0.044 C: 2.417 D: 0.44

数据3.21450保留4位有效数字,按照修约规则的结果是3.214

设[tex=4.786x1.214]99Oi9AZizu+X9PK5CBb8uXcHB+2+6ZE78oUe76WDeeg=[/tex]（1）证明它满足方程[tex=17.286x1.643]Ztc4eTjZTO/VJdqS0ZxH2eGEleL1xb1t1fPsZrVT951ymaAbMG2Xks6pkpmDk5oMnewhI1QxqzAeV46OVTR8nwCa17a6zQV8omb2tsAoyNs=[/tex]（2）求[tex=3.214x2.214]sxdWfpQMRl0A8KEL2m8t2gG2HdrVL8eMqi42J2PaLYpG4z4bpFCpaaQisrIWH8z+[/tex]                  

‎下列测量结果中，测量准确度最低的是‍ A: (154.98±0.02)mm B: (5.498±0.002)mm C: (1.5498±0.0002)mm D: (2.214±0.001)mm

设[tex=4.786x1.214]PjtRFRL7Sy94PtSENeLoqg==[/tex](1) 证明它满足方程[tex=5.786x1.643]6jV4hMVdT6/sjY51fXWSf9Jwq1SjXVPi2Xe6XJ0/gHM=[/tex][tex=6.929x1.571]fNC6tpSPgCOoQChaclEkD4iwQs5t1FwxXwbR4xocMlo=[/tex][tex=7.786x1.571]trW7pXRKoSKm5PoydaBOmxOYrgqQRWEfNtGiyXGTCZg=[/tex](2) 求[tex=3.214x2.214]X7UJcpr5wALnuq63VNMT5pYA9rtR+V5FIV1OLail3wQ=[/tex]

设 [tex=5.071x1.214]wrSnlUtj+rKzdbn82Phzvw==[/tex], 则下式中正确的是. 未知类型：{'options': ['[tex=4.571x2.5]kob8gle60P3uEPjQtewWMXnWG9OEZQRKI66K1J02OjcHelDkvM9KVTPeMWw5sX3s[/tex]', '[tex=3.214x2.214]kob8gle60P3uEPjQtewWMVGeRJE+EBvBIqvkThMWH6FvhUqHsI9Cb+19CO404Ep7[/tex]', '[tex=3.643x2.5]kob8gle60P3uEPjQtewWMVGeRJE+EBvBIqvkThMWH6FE35P6Sth17+E2Kr7WTCcH[/tex]', '[tex=3.929x2.429]kob8gle60P3uEPjQtewWMVGeRJE+EBvBIqvkThMWH6HFwsf10lm/Wzb5GE1CYAxU[/tex]'], 'type': 102}

下列变量组（）是一个闭回路。 A: {x，x，x，x，x，x} B: {x，x，x，x，x} C: {x，x，x，x，x，x} D: {x，x，x，x，x，x}

以下谓词蕴含式正确的是（）: (∀x) (A(x)→B(x))=>( ∀x)A(x)→(∀x)B(x)|(∀x) (A(x)↔B(x))=>( ∀x)A(x)↔(∀x)B(x)|(∀x)A(x)∨(∀x)B(x)=>( ∀x) (A(x)∨B(x))|(∃x) (A(x)∧B(x))=>(∃x)A(x)∧(∃x)B(x)

以下谓词蕴含式正确的是（）: (?x) (A(x)→B(x))=>( ?x)A(x)→(?x)B(x)|(?x) (A(x)?B(x))=>( ?x)A(x)?(?x)B(x)|(?x)A(x)∨(?x)B(x)=>( ?x) (A(x)∨B(x))|(?x) (A(x)∧B(x))=>(?x)A(x)∧(?x)B(x)

下列式中错误的是： A: (∀x)(A(x)Úp(x)) Û (∀x)A(x)Ú (∀x)p(x) B: ($x)A(x) Ù p Û ($x)(A(x) Ù p ) C: (∀x)(A(x)ÚB(x)) Þ (∀x)A(x)Ú( ∀x)B(x) D: ($x)(A(x)ÙB(x)) Þ ($x)A(x)Ù( $x)B(x)