data temp_01;infile cards dsd dlm=" ";
input a b c d;
cards;
''54'' ''75'' ''253'' ''44''
''87'' ''3'' ''55'' ''456''
''905'' '''' ''66'' ''354''
;

data temp_02;
infile cards dsd dlm='' '';
input name $ 1-15 @17 number $ 6. street $ 24-42;
cards;
" John Garcia"   "1111" "Maple Ave"
"Sylvia Chung"  "1302" "Washington Drive"
"Martha Newton" "45"  "S.E.14th St"
"Hommiege"       "34"  ""
;
请问一下，问什么在第二个例子当中不能用DSD选项将引号去掉？