句型转换（将下列陈述句括号内的内容变为强调句）

句型转换（将下列陈述句括号内的内容变为强调句）
1.（The children）often help their parents do the farm work.2. (In 1993),a tomato was developed that was very different from any grown before.3. The biggest problem of china farmers is (the shortage of arable land).4. Future agriculture should depend on(high technology as well as traditional methods )