【单选题】拮抗多巴胺对以及的β1-受体作用的是( )
【单选题】Don't be discouraged. Have___ try.
【单选题】Don't be discouraged ______ you have fallen behind others.
【单选题】— I'm afraid I have to give it up. — Don't be discouraged. Remember _____ sticks to his work will succeed one day. [ ]
【单选题】— I failed my driving test again. — Don't be discouraged. You'll be successful ________.
【单选题】Don't be discouraged. Have ___ try.
【单选题】学习运算符+= 表达的含义;%=表达的含义;.=表达的含义。 $a += $b; 相当于 $a = $a + $b; $a %= $b;相当于 $a = $a%$b; $a .= $b; 相当于 $a =$a$b; .=是连接两个变量,主要用于字符串的连接。 下述各选项中,哪( )项是正确的。
A.
$a += $b; 相当于 $a = $b;
B.
$a %= $b;相当于 $a = $a%$b;
D.
$a .= $b; 相当于 $a =$a/$b;