[填空题]So far, there seems to be no solution in sight as to how the hydrogen can be stored.

[填空题]So far, there seems to be no solution in sight as to how the hydrogen can be stored.

[填空题]So far, the robot seems to be the best, servant in the house. You can {{U}} (36) {{/U}} it to different tasks: polish the floors, dust the {{U}} (37) {{/U}}, clean the windows. But a new kind of robot has many other {{U}} (38) {{/U}}. When a guest arrives at the door, it can say "Can I help you, please " and takes his cap. If you give the right {{U}} (39) {{/U}}, it can even serve dinner to you at the table. If someone breaks into the house, the robot will sound the {{U}} (40) {{/U}} and "speak" to the thief. It is {{U}} (41) {{/U}} to "notice" any signs of fires or changes to "tell" its owner about them. What is more, it has a basic {{U}} (42) {{/U}} of 250 English words, but if {{U}} (43) {{/U}}, it can speak any language. Many owners will be glad when this servant friend stops working and leaves themselves alone. {{U}} (44) {{/U}}. One robot of this kind recently took a holiday and came to London. {{U}} (45) {{/U}}. "This is my birthday," he said, "Fin happ