有X、Y两种元素,原子序数≤20,X的原子半径小于Y,且X、Y原子的最外层电子数相同(选项中m、n均为正整数)。下列说法正确的是( )
Ann has got a letter from her best friend.It makes ___________ quite excited.
she
her
hers
herself
Listen!Our science teacher _______________the use of the robot.
explains
explained
is explaining
has explained
There are many_____________ teachers in this primary school.
woman
woman's
women
women's
The Tianwen﹣1 Probe landed on Mars___________ May 15th,2021.
at
in
to
on
Taking the train is _________good way to see the world.
a
an
the
/