American women usually identify their best friends as someone _______ they can talk frequently.
A:who
B:as
C:about which
D:with whom
①12-02=1+0=1;
②22-12=2+1=3;
③32-22=3+2=5
④42-32=4+3=7;
⑤52-42=5+4=9
若字母n表示自然数,请把你观察到的规律用含字母n的式子表示出来:
____.
分一分
38个气球,每6个扎成一束,可以扎成____束,还剩____个。