Since the second joiner method calls the first, it requires an explicit String return type.

因为第二个jioner 方法调用了第一个，它需要一个显示的String 返回类型。

youdao

Scala can usually infer the return type of the method (but not the types of the method arguments), so we drop the explicit declaration.

Scala 通常可以推断出方法的返回值（但是方法参数的类型就不行了），所以我们不用显式声明。

youdao

The exact and explicit solutions of these equations are obtained by using the travelling wave method. These exact solutions are solitary wave solutions of a rational type.

用行波方法得到了这些方程的显式精确解，即有理分式型孤立波解。

youdao